The present invention relates to an exercising machine for performing the act of chinning oneself which is simple in structure and inexpensive to manufacture.
A variety of exercising machines have been disclosed for exercising different parts of the body, and have appeared on the market. There is an exercising machine specifically designed for performing the act of thinning oneself. This pull-up exercising machine, as shown in FIG. 1, is generally comprised of a base frame 10, an upright back frame 11, a bevel front frame 12, a horizontal top frame 13, two hand grips 21 bilaterally extended downwards from the horizontal top frame 13, two handrails 22 bilaterally connected to the bevel front frame 12 in the middle and disposed in horizontal, a supporting arm 14 having a rear end pivotably fastened to the upright back frame 11 by a pivot 20 and a front end attached with a platform 19, a foot stool 18 mounted on the base frame 10, and a pull rope 16 having one end fastened to the bevel front frame 12 and an opposite end passing through a plurality of pulleys 17 to carry weights 15. When the user stands on the platform 19, the supporting arm 14 is forced to turn downwards causing the weights 15 to be lifted. When the player pulls the body up, the supporting arm 14 is lifted to its former horizontal position by the pressure of the weights 15. Because this structure of pull-up exercising machine is bulky, heavy, and expensive, it is still not popularly accepted. Another drawback of this structure of pull-up exercising machine is that the platform 19 will be turned to a sloping position when the supporting arm 14 is lowered, and therefore the user may slip from the platform 19.
U.S. Pat. No. 4,846,458 discloses a similar apparatus for performing the act of chinning oneself, which uses two sets of four-bar linkages to keep the platform constantly maintained in a horizontal position, and an adjustable hydraulic cylinder serves to stabilize the movement of the platform. This structure of exercising machine is very expensive and difficult to maintain, and therefore its market is limited only to gymnastics centers and professional clubs.